The present invention concerns an optical pickup device used for reading and writing optical recording media such as compact disks (CD), digital versatile disks (DVD), and blue-ray disks (BD), or an optical disk drive unit incorporated with the optical pickup device.
The optical pickup device used for reading and writing optical recording media such as CD, DVD, and BD, or the optical disk drive apparatus incorporated with the optical pickup device includes an optical system of guiding a light emitted from a light emitting device such as a laser diode by way of various types of lenses, prisms, mirrors, etc. to an object lens and focusing the same on an optical recording medium and an optical system of receiving a light returned from the optical recording medium by an optoelectronic conversion device by way of an object lens and other various kinds of lenses, prisms, and mirrors and converting an optical output into an electric signal. Among them, it is necessary that an optical part module having a modularized laser diode is fixed to an optical pickup case at an optimal position by using an adhesive with an optical point of view. Therefore, in the structure of adhesively fixing the optical part module, only the front surface of the optical part module is bonded with a view point of positional stability.
As the thickness of the optical pickup device is decreased, in a case of a structure of bonding a thin optical part module only at the front surface, a load from a flexible printed substrate or an external load tends to exert like a binding moment on the bonding portion to result in a problem of lowering the bonding reliability such as deterioration of impact resistance. Further, in a case of a structure of adhesively fixing the optical part module bonded not only at the front surface but also at the lateral surface, while the resistance to the bending moment increases, a stress due to circumstantial changes is generated directly to the bonding portion at the lateral surface. Accordingly, peel at the bonding boundary proceeds gradually to bring about a problem of lowering the bonding reliability.
Accordingly, for a thin optical pickup device, it is necessary to provide an adhesively fixing technique capable of maintaining an optimal position at a high positional accuracy even in a case when a stress due to an external load by bending moment or due to circumstantial changes is generated to the optical module.
For the structure of adhesively fixing a laser unit to improve the positioning reliability thereof, JP-A No. 2004-178626 discloses that an optical pickup having high reliability also against repulsion from a flexible substrate and circumstantial changes can be provided in an optical pickup in which an adhesive is filled in a gap between an optical pickup case and a plate for holding a laser unit for adhesively fixing them, by forming a concave portion or a convex portion at two positions on one bonding surface of a plate for holding the laser unit.